Patent Application
20210012980
The present invention relates to lock-off mechanisms for triggers of electrical devices such as power tools, gardening tools and the like for locking-off the trigger from operation.
Electric power tools will often include a trigger member that is squeezed towards a main body of the tool to actuate operation of the tool motor. The tool will also typically include a lock-off mechanism which is a safety mechanism that can be operated to prevent the trigger member from being inadvertently squeezed and the electric device being turned on. With certain lock-off mechanism designs, the lock-off member is rotatably mounted on to the trigger member and is dependent on the trigger device to function properly. Hence if the trigger member is damaged, for instance due to heat stress deformation, operation of the lock-off mechanism may also be compromised so as to pose a risk of harm to the user. Further, the components of existing lock-off mechanisms often tend to be readily exposed to the environment and are thus subject to degradation and wear and tear which may not only cause the lock-off mechanism to fail but is also unsightly to the user.
The present invention seeks to alleviate at least one of the above-described problems.
The present invention may involve several broad forms. Embodiments of the present invention may include one or any combination of the different broad forms herein described.
In one broad form, the present invention provides a trigger assembly for use with an electrical device, said trigger assembly including;
a main body having an electric switch housing within which an electrical switch unit is disposed therein;
a trigger member having an engagement portion that is hingedly connected to the main body of the trigger assembly so that the trigger member is rotatable about a hinge relative to the main body, said trigger member also including a first wall and sidewalls defining a trigger member space therebetween;
an actuator member operably-connected to the trigger member wherein, responsive to rotational movement of the trigger member about the hinge relative to the housing, said actuator member is movable in a first direction relative to the housing from an OFF position in which an electrical switch of the electrical device is operably-opened by the actuator towards an ON position in which the electrical switch is operably-closed by the actuator, and is movable in a second direction relative to the housing from the ON position towards the OFF position; and
a lock-off mechanism including a lock-off member that is selectably operable to restrict movement of the trigger member towards the main body and to thereby restrict movement of the actuator member from the OFF position into the ON position, and, to not restrict movement of the trigger member toward the main body and to thereby allow movement of the actuator from the OFF position in to the ON position;
wherein the main body includes at least one rigid arm having a first end connected with a surface of the main body and extending away from the main body into the trigger member space terminating at a second end that is spaced apart from the first end, and wherein, said lock-off member is rotatably mounted proximate to the second end of the at least one rigid arm; and
wherein the trigger member includes an aperture disposed therein and is configured so that a user may rotatably operate the lock-off member about the second end of the arm via the aperture in the trigger member.
Preferably, the aperture is configured so that when the lock-off member is operated to restrict movement of the trigger member towards the main body, a portion of the lock-off member is configured to protrude outwardly through the aperture.
Preferably, the present invention include a pair of rigid arms extending outwardly from the main body, and wherein the lock-off member rotates about a hinge pin that is rotatably mounted between respective second ends of each of the pair of rigid arms.
Preferably, the present invention includes a biasing element operably-connected between the lock-off member and a surface of the main body of the trigger assembly so as to bias the lock-off member into the position in which it does not restrict movement of the trigger member toward the main body. Also, preferably, the biasing element includes a return spring.
The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiments thereof, described in connection with the accompanying drawings, wherein:
Preferred embodiments of the present invention will now be described herein with reference to
The variable-speed trigger assembly (100) includes a hand-operable trigger member (130) that is rotatably movable about a hinge (133) relative to a main body (120) of the trigger assembly (100). The trigger member (130) includes a first wall (130A) and sidewalls (130B) defining a trigger member space (130D) therebetween. An aperture (130C) is disposed in the first wall (130A) of the trigger member (130) as shown in
The trigger member (130) is also operably-connected to an actuator member (150) whereby, when the trigger member (130) is squeezed towards the main body (120), the actuator member (150) is configured to move in a direction inwardly of the housing (120A) from an OFF position towards an ON position. When the user's hand releases the trigger member (130), the return spring urges the trigger member (130) in a direction away from the main body (120), and consequently, the actuator member (150) is also caused to move in a direction outwardly of the housing (120A) from the ON position toward the OFF position. The actuator member (150) is operably-connected to the electrical switching contacts such that in response to the actuator member (150) being moved in to the ON position, the electrical switching contacts are moved in to a closed-circuit arrangement whereby power from the DC power source can be supplied to the brushless DC motor via the pair of electrical switching contacts. Conversely, in response to the actuator member (150) being moved back in to the OFF position by movement of the trigger member (130) away from the main body (120), the pair of electrical switching contacts are moved in to an opened-circuit configuration whereby the DC power source is not able to supply power to the brushless DC motor via the pair of electrical switching contacts. The actuator member (150) is also movable through a range of ON positions inwardly of the housing (120A) depending upon the amount of squeezing force applied to the trigger member (130) by the user's hand and the DC motor is configured to operate at variable speeds of operation depending upon the degree of movement of the actuator member (150) inwardly of the housing.
A lock-off mechanism is provided which includes a lock-off member (140) that is selectably operable to restrict movement of the trigger member (130) towards the main body (120) and to thereby restrict movement of the actuator member (150) from the OFF position into the ON position, and, to not restrict movement of the trigger member (130) toward the main body (120) and to thereby allow movement of the actuator (150) from the OFF position in to the ON position. In this embodiment the main body (120) includes a pair of rigid arms (121A,121B)) each having first ends connected with a surface of the main body (120) and extending away from the main body (120) into the trigger member space (130D) terminating at respective second ends that are spaced apart from the first ends of the rigid arms (121A,121B). The lock-off member (140) is rotatably mounted about a hinge pin (135) that extends between the second ends of the rigid arms (121A,121B). A return spring (136) is operably-connected between the lock-off member (140) and a surface of the main body (120) so as to bias the lock-off member (140) into the position in which it does not restrict movement of the trigger member (130) toward the main body (120). The lock-off member (140) and aperture (130C) in the trigger member (130) are suitably configured so that a user may rotatably operate the lock-off member (140) about the second end of the arm via the aperture (130C) in the trigger member (130). When the lock-off member (140) is rotatably arranged to restrict movement of the trigger member (130) towards the main body (120) such as shown in
Advantageously as the lock-off assembly is mounted to the main body (120) of the trigger assembly and not to the trigger member (130), it operates independently of the trigger member (130). As such, in the event of damage or failure in the trigger member (130), for instance, due to heat stress deformation, the lock-off (140) assembly will continue to operate effectively to ensure that the electrical device cannot be switched on when locked-off. In contrast, in certain conventional trigger assemblies (200) of power tools, for instance such as shown in
Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described without departing from the scope of the invention. All such variations and modification which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps and features, referred or indicated in the specification, individually or collectively, and any and all combinations of any two or more of said steps or features.
The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19126545.3 | Jul 2019 | HK | national |
